By Johannes Preiser-Kapeller
Historical Dynamics of Byzantium, No. 1 (2010)
Introduction: In the last decade, historical and social studies have been confronted with a new kind of scientific research on natural as well as social, economic and historical phenomena based on the concept of complex systems; one may even speak of a “complexity turn”. Quantitative and mathematical methods and models are used to analyse social processes and structures, and it is suggested that these models capture dynamics of real-world phenomena and even have some predictive value. At the same time, these new methods claim to be more adequate for the analysis of social and historical dynamics than earlier attempts at the “calculation” of history which were based on the mechanistic thinking of 19th century natural sciences; one prominent researcher in the field of “historical dynamics”, Peter Turchin, even claims that only with these methods “historical sociology (will) become a theoretical, mature science”.
Especially the theses of Peter Turchin, Professor of Ecology and Evolutionary Biology, found favour (but also critics) among various scholars in the fields of socio-historical research – but less so among specialist historians. One cause for the appeal of Turchin’s model may be his usage of relatively comprehensible mathematics; a reviewer gratefully wrote “the author eschews the hyper-parameterized, computer-dependent approach found in many contemporary modelling efforts, and instead focuses on variants of three basic and well understood differential equation models: the exponential, logistic, and predatorprey.“ The reviewer may have in mind models such as those of Wolfgang Weidlich in his book on “Sociodynamics”; for his model for “the rise and fall of interacting social groups” Weidlich used 15 Key-variables and 30 “Trend-functions” and at the same time stated: “we restrict the model to one sector or one dimension of social life”. Peter Turchin on the contrary claimed to be able to explain in his book “Historical Dynamics” on 240 pages “Why States Rise and Fall”.
But can these models really provide any further insight into the development of a medieval society such as Byzantium? One limiting factor is the necessity to provide statistical material in order to evaluate the appropriateness of a quantitative model – material which in most cases for the Byzantine period simply does not exist. To evaluate for instance Weidlich’s model of “the rise and fall of interacting social groups” we would need figures for the numbers of followers of the various political and ecclesiastical factions in 14th century Byzantium. Turchin’s simpler models demand less specific data, but still rely mostly on historical statistics to a degree which we are not able to provide on the basis of Byzantine sources.